A dielectric film containing a Si—N including a silicon nitride (SiN) film and a silicon carbonitride (SiCN) film has high resistance against hydrogen fluoride (HF). Therefore, in a manufacturing process of a semiconductor device such as a memory, a large scale integrated circuit (LSI), and the like, the dielectric film may be used as an etching stopper layer at the time of etching a silicon oxide (SiO2) film, or the like, a film for preventing a deviation increase of resistance of a gate electrode or diffusion of a dopant, or the like. Particularly, there is a need to decrease a film formation temperature of a silicon nitride film after forming the gate electrode. For example, at the time of forming the silicon nitride film after forming the gate electrode, the film formation temperature should be lower than 760° C., which is a film formation temperature in the case of using low pressure-chemical vapor deposition (LP-CVD) according to the related art, or 550° C., which is a film formation temperature in the case of using atomic layer deposition (ALD).
The ALD is a method of alternately supplying one of two kinds (or more) of source gas used for film formation onto a substrate under arbitrary film formation conditions (temperature, time, and the like) to adsorb the gas in a unit of one atomic layer, and performing film formation using a surface reaction. For example, a film having a thickness corresponding to one molecular layer is formed by alternately flowing first source gas and second source gas along a surface of an object to be treated to adsorb source gas molecules of the first source gas in the surface of the object to be treated and reacting source gas molecules of the second source gas with the adsorbed source gas molecules of the first source gas. In addition, a film having high quality is formed on the surface of the object to be treated by repeating this step.
A silicon nitride film capable of being formed at a low temperature of 300° C. to 600° C. by supplying an ammonia radical (NH3*) obtained by activating ammonia with plasma in the case of alternatively supplying dichlorosilane (DCS: SiH2Cl2) and ammonia (NH3) using ALD has been disclosed in Japanese Patent Laid-Open Publication No. 2004-281853. However, in the silicon nitride film formed at a low temperature using ALD, a concentration of chlorine (Cl) that is a factor affecting natural oxidation of the silicon nitride film or deteriorating resistance of the silicon nitride film against hydrogen fluoride is increased, such that a wet etch rate is large, and thus, etching selectivity (selection rate) to an oxide film is small. Further, the silicon nitride film formed at a low temperature has low film stress, such that it is impossible to implement desired stress intensity. A method of introducing carbon (C) in the silicon nitride film to improve resistance against hydrogen fluoride may be suggested, but in a low temperature region of 400° C. or less, introduction of carbon in the silicon nitride film may cause a structural defect, such that a dielectric property may be deteriorated.
Therefore, the present inventors tried to provide a manufacturing method of a dielectric film containing a Si—N bond having excellent cohesive force, a high deposition rate, and excellent physical and electrical properties even at a low temperature by using atomic layer deposition, thereby completing the present invention.